const fs = require("fs");
const readFile = function (filename) {
  return new Promise((resolve, reject) => {
    fs.readFile(filename, (err, data) => {
      if (err) reject(err);
      resolve(data);
    })
  });
};
let fn = async function () {
  try {
    let f1 = await readFile("1/a.txt");
    let f2 = await readFile("1/b.txt");
    let f3 = await readFile("1/c.txt");

    console.log(f1.toString(), f2.toString(), f3.toString());
  } catch (err) {
    console.log(err);
  };
};
fn();